Expression of vascular endothelial growth factor in cultured human dental follicle cells and its biological roles

Aim: To investigate the expression of vascular endothelial growth factor (VEGF) in cultured human dental follicle cells (HDFC), and to examine the roles of VEGF in the proliferation, differentiation, and apoptosis of HDFC in vitro. Methods: Immunocytochemistry, ELISA, and RT-PCR were use to detect the expression and transcription of VEGF in cultured HDFC. The dose-dependent and the timecourse effect of VEGF on cell proliferation and alkaline phosphatase (ALP) activity in cultured HDFC were determined by MTT assay and colorimetric ALP assay, respectively. The effect of specific mitogen-activated protein kinase (MAPK) inhibitors (PD98059 and U0126) on the VEGF-mediated HDFC proliferation was also determined by MTT assay. The effect of VEGF on HDFC apoptosis was measured by flow cytometry. Results: VEGF was transcribed and expressed in cultured HDFC. VEGF at 10-300 mu g/L significantly increased HDFC proliferation adn ALP activity compared to the control. Following 1, 3, 5, or 7 d of stimulation, VEGF induces a significant increase in HDFC proliferation compared with the corresponding control, while VEGF was effective at increasing ALP activity at the incubation time point of 3, 5, or 7 d. PD98059 and U0126 could attenuate the VEGF-mediated HDFC proliferation. Fewer apoptotic cells were observed in the VEGF-treated groups compared to the controls, although the difference was not statistically significant. Conclusion: VEGF is expressed in cultured HDFC to differenciate in a "cementoblast/osteoblast" pathway and protect HDFC form apoptosis. The MAPK signaling pathway might be involved inthe VEGF-mediated HDFC proliferation.